Monday, March 10, 2008

Comet C/2008 E3 (GARRADD)

IAU circular nr. 8927 published yesterday, announces the discovery of a new comet by Gordon Garradd, named C/2008 E3 (GARRADD). This object has been picked-up on 2008, March 5.8 on images obtained within the Siding Spring 0.5m Uppsala schmidt reflector + CCD.

We peformed some follow-up of this object by means of a remotely controlled scope of the "RAS" network (details on image; click on it for a bigger version):

In our stacking we can appreciate a coma nearly 10 arcsec in diameter, with a strong central condensation. Through strong enhancement of the visualization parameters, a faint and extended outer halo nearly 20arcsec in diameter, possibly elongated toward North-West, seems to be visible (however it must be said that in our frames this detail is very close to the background noise, and thus must be considered as uncertain).

It's also possible to see a faint and broad tail, extending nearly 20 arcsec toward North. We measured the central condensation as m2 almost 18.4, while the 10 arcsec coma has an m1 nearly 17.7 (both are unfiltered CCD magnitudes, approximated to R).

A preliminary afrho (proxy of dust abundance within the coma) measurement provides a value close to 450 +/- 100 cm; this seems to point toward a pretty active comet, considered that it's current distance from the Sun is r~ 5.5 AU.

The Minor Planet Center database points to a (preliminary) retrograde parabolic orbital solution with an inclination on the ecliptic plane of i~ 107 degrees; perihelion will be reached at the end of next October, at 5.2 AU from the Sun.

C/2008 E3 (GARRADD) will remain a southern hemisphere object, and it's not supposed to get significantly brighter than magnitude 17.

Ernesto Guido & Giovanni Sostero

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